11 3/4 brakes

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BigBlockMopar said:
Pics of the setup someone above 'couldn't see working'... ;)

I do need to change the stock MC for one with a larger diameter as the brakepedal-travel is fairly large now.
But that's because the stock '73 front brakecalipers have a 2.597" piston-diameter, and the '73 Chrysler caliper has a 2.752" piston-diameter. More fluid to move.
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First off, I initially said it wouldn't work because you incorrectly identified your caliper brackets as being from a C-body, which do have a different bolt pattern.

Now that we know you have B body caliper brackets, I can see how you can run C body rotors and calipers, I just no longer see why. You have the b-body caliper mounts, which are the hardest part to find. You have the '73+ spindles. So, you can straight up bolt on B/R body 11.75" rotors and use A/B/E/F/M/J calipers, all of which would be easier to find parts for.

But, instead you're using bearing collars and spacers to make C body rotors and calipers work. Sure, it'll take a lot more to heat up your rotors, but unless you're doing some SERIOUS racing you wouldn't have any issues with the 1" x 11.75" rotors. And you've added a ton of weight. I suppose it might be a little cheaper if you had the rotors and calipers already, but it just seems like a lot of extra work for pretty much zero benefit to me.
 
You can make 'em work, but the '73-up A spindles w/the 11 3/4" rotors and adapter from a Cordoba, St.Regis, "Last of the B-bodies" have more than enough clamping and heat dissipation for A-bodies. Anything more is just more reciprocating weight you have to get in motion and then slow down that you have to adapt to work-I like decaf and dry humping as much as the next guy, but...
 
Just a little more on the brake issue. If you can find the December 2012 issue of Mopar Action there is a great article on solving the rear brake lock-up problem. They use a anti lock system from a later model Chrysler product. No sensors to install just a modulator and controller plumbed into the rear brake line. Read the article on page 62, time to haunt the JY's again! One more thing, the 11.75 slider adapters are now available new on ebay for 100.00 shipped. I just ordered mine.
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=180964477859
 
Robbie2734 said:
Just a little more on the brake issue. If you can find the December 2012 issue of Mopar Action there is a great article on solving the rear brake lock-up problem. They use a anti lock system from a later model Chrysler product. No sensors to install just a modulator and controller plumbed into the rear brake line. Read the article on page 62, time to haunt the JY's again! One more thing, the 11.75 slider adapters are now available new on ebay for 100.00 shipped. I just ordered mine.
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=180964477859
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Doctor Diff product I see :cheers:
 
I found that the complete setup from a 78 cordoba fir onto my 74 A body spindles like the factory planned it that way. 20,000+ miles later if still stops on a dime. The cost of the new rotors were only $65.00 each, and thats up here in Canada.
 
The new caliper brackets just arrived. They are brand new and are look great, time to order the rotors!
 
dodge freak said:
Sounds great but are they from China ? Not saying its bad, just wondering who is making them
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Here are some pics, there are no markings on them, but they seem to be well made. I'll know more about fit when I do the conversion to 11 3/4 rotors.
 

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very cool!! I have my eye on a set. wanna upgrade from the 10.87" as well....keep us posted..:)
 
I finally got the parts together for the larger disks, and since it's a rainy day here I worked on the car. Here are some pics of the conversion, and the old and new rotors side by side. I haven't driven the car yet but it should stop great now. I have 11 X 2 1/2 drums on the back and hope this balances the system. The rear would lock first with the 11 inch disks, I don't think it would be a problem If I had 10 inch drums in the rear. One note to add, you will need longer bolts for the caliper brackets, I used the ones I had from the van parts.
 

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very cool! thank you for the update. looks like they will work great. where would i be able to find the longer bolts?
 
If your rears still lock first there are two things you can change that will affect the balance. First, 73-75 A-bodies used calipers with smaller pistons. Switching to the large piston calipers (76 A, later B, F, R etc...) will increase front braking. If that doesn't solve the problem, look for rear wheel cylinders with smaller diameter pistons. I think I've seen some 13/16" or even 3/4" wheel cylinders out there somewhere.
 
1/2 inch fine thread grade 8 bolts will be just fine, get the length needed.
 
If you're dying for original bolts, trucks have the longer ones too. Don't see why you would need them if new works for you, though. Just an FYI.
 
DionR said:
If you're dying for original bolts, trucks have the longer ones too. Don't see why you would need them if new works for you, though. Just an FYI.
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I'm definitely not dying for ''original'' bolts!! I'm 100% happy with grade 8 bolts from Ace hardware!!
 
The original bolts will work but they are short. The replacement brackets are thicker by about 1/2 inch. You can see the stud ends from the van brackets sticking through the rotor cover, just like the 11 inch bracket bolts did. I knew I'd get some use out of the van disks!! It was a very easy job, everything just bolts into place. Next step might be to go with the larger 76 calipers. I'll see how this works, I have a bad feeling if I use the larger calipers I'll need to go with a larger bore M/C.
 
Just a couple more pics
 

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I did this swap to my 64 sport fury. Used late B body caliper brackets with the 76 f body style calipers and a 74 A body prop valve. I had to go from a 15/16 bore mc with the old 10.87 rotor and smaller 74 A bodycaliper to a 1 1/32 bore mc with the larger calipers. I have 11 inch rear brakes from a 69 RR. So far I'm not impressed with the braking. seems the same as with the smaller rotor/caliper. Any thoughts? Sorry for hijacking but the answer may help others.
 
furyus2 said:
I did this swap to my 64 sport fury. Used late B body caliper brackets with the 76 f body style calipers and a 74 A body prop valve. I had to go from a 15/16 bore mc with the old 10.87 rotor and smaller 74 A bodycaliper to a 1 1/32 bore mc with the larger calipers. I have 11 inch rear brakes from a 69 RR. So far I'm not impressed with the braking. seems the same as with the smaller rotor/caliper. Any thoughts? Sorry for hijacking but the answer may help others.
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Interesting. I run the exact same set up on my Challenger, and the braking is markedly better than with the small disks. It doesn't feel much different under normal braking conditions because of the power brakes, but it stops much faster under harder braking conditions. Some of that is the larger tires though, if you were locking up the small brakes then there's no reason why you wouldn't do the exact same thing with the larger ones, and you might not notice a difference. With 275/40/17's grabbing the pavement all the way around, the big brakes on my Challenger really get a work out.

What pads and shoes are you running? If its new stuff, is it semi-metallic? A change from semi metallics on the small brakes to organic pads on the large brakes would definitely negate some of the advantage. Nice new brake fluid? Rebuilt calipers? New wheel cylinders? Rear brakes adjusted properly? New brake lines? What size wheel cylinder bores?

Leaky seals, contaminated fluid or pads/shoes, old rubber brake lines, air in the lines, leaky vacuum booster if power, all will do a number on your braking.
 
72bluNblu said:
Interesting. I run the exact same set up on my Challenger, and the braking is markedly better than with the small disks. It doesn't feel much different under normal braking conditions because of the power brakes, but it stops much faster under harder braking conditions. Some of that is the larger tires though, if you were locking up the small brakes then there's no reason why you wouldn't do the exact same thing with the larger ones, and you might not notice a difference. With 275/40/17's grabbing the pavement all the way around, the big brakes on my Challenger really get a work out.

What pads and shoes are you running? If its new stuff, is it semi-metallic? A change from semi metallics on the small brakes to organic pads on the large brakes would definitely negate some of the advantage. Nice new brake fluid? Rebuilt calipers? New wheel cylinders? Rear brakes adjusted properly? New brake lines? What size wheel cylinder bores?

Leaky seals, contaminated fluid or pads/shoes, old rubber brake lines, air in the lines, leaky vacuum booster if power, all will do a number on your braking.
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It's not locking up. Just feels like I press on the pedal and it takes too long to slow down. I will check on the pads. I can't remember if they are semi-metallic or not. Fluids fairly new from the swap, calipers rebuilt,wheel cylinders were replaced a few years ago. Not sure of the size. Stock for 69 RR. Need to look that up.lines are new. No air in the lines or leaks. Been considering power brakes. Will they work with 12 inches of vacuum?
 
Brakes work much better, I would like to know what is a good pad. It's time to replace the old ones and I'm looking for a good hi performance pad.
 
Ebc makes the red stuff pads for this setup (bigger bore piston at least).
 
furyus2 said:
It's not locking up. Just feels like I press on the pedal and it takes too long to slow down. I will check on the pads. I can't remember if they are semi-metallic or not. Fluids fairly new from the swap, calipers rebuilt,wheel cylinders were replaced a few years ago. Not sure of the size. Stock for 69 RR. Need to look that up.lines are new. No air in the lines or leaks. Been considering power brakes. Will they work with 12 inches of vacuum?
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Could also be that your pads are contaminated, just a little oil or grease will seriously decrease your braking performance. Are they new? If they're brand new and you don't have many miles on them, its also possible that they might not be fully broken in yet. But thats a very short mileage issue, should go away pretty quickly.

Power brakes are ok, I actually prefer the manuals on my Duster vs the power brakes on my Challenger. Duster also runs 11 3/4" disks. Again, I thought it was a very noticeable difference. That is comparing old worn out 10.87" disks vs. brand new 11.75" disks with new pads, but the same old calipers and fluid. I'm not exactly sure of the vacuum numbers you need, although I believe 12" is borderline for power brakes. If you want to go that route you might have to install a vacuum canister. Or go hydroboost, as that seems to be the latest and greatest.

Robbie2734 said:
Brakes work much better, I would like to know what is a good pad. It's time to replace the old ones and I'm looking for a good hi performance pad.
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Depend on how high performance you want to go. Anything semi-metallic should be fine for a driver/street car, I just stay away from the "organic" pads as they don't tend to perform as well. Firm Feel sells carbon metallic pads, which are a great high performance pad. But they're pretty spendy as well.
 
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